Radio-frequency applicator with electroscopic control



April 1938. E. R. HAYFORD 2,114,345

RADIO-FREQUENCY APPLICATOR WITH ELECTROSCOPIC CONTROL Filed April 10,1934 INVENTOR v Patented Apr. 19, 1938 PATENT OFFICE RADIO-FREQUENCYAPPLICATOR WITH ELECTROSCOPIO CONTROL Elmer R. Hayford, Rochester, N.Y., assignor, by mesne assignments, to Joseph K. Davidson,

Rochester, N. Y.

Application April 10, 1934, Serial No. 719,978

5 Claims.

My present invention relates to electrical devices and more particularlyto the generation, use and control of radio frequency power, and it hasfor its object to provide an apparatus of this character that will besimple in construction and operation and by means of which theradio-frequency power may be put to such uses as destroying bacteria andother small animate life. A further object of the invention is toprovide automatic means for controlling radio frequency output from agenerator through an output inductance element, preferably, to a fieldinductance correlated or coupled therewith whereby an electrostaticfield maintained across the inductance may be regulated for thedissipation in matter placed therein of all electrostatic energy withoutchanges of any consequence in the power derived from the radio-frequencygenerator.

To these and other ends, the invention resides in certain improvementsand combinations of parts, all as will be hereinafter more fullydescribed, the novel features being pointed out in the claims at the endof the specification.

In the drawing:

Fig. 1 is a top plan composite view of an apparatus constructed inaccordance with and illustrating one embodiment of my invention, partsthereof being conventionally illustrated and the view being partiallydiagrammatic to include in enlarged side elevation the compensating orcontrolling device for the electrostatic field of the capacityelectrodes;

Fig. 2 is a transverse section taken on the line 2-2 of Fig. l, and

Fig. 3 is an elevation of the controlling device taken from anotherside.

Similar reference numerals throughout the several views indicate thesame parts.

Referring more particularly to the drawings, I indicates a base uponwhich is shown mounted at one end the tubes 2 and condenser 3 having theusual knob control 4 of a radio-frequency generator. The condenser isconnected by wires 5 with an output inductive element 6 in the form of acoil having its circuit-connected ends supported on insulated standardsI on the base. Opposite this coil is a similar inductive electromagneticfield coil 8 similarly mounted on insulated standards 9. Beyond this areinsulated tables H) on the base supported by standards H on which arearranged in spaced opposition to each other two capacity electrodes I2.These are, respectively, connected by wires I3 to the terminals of 8,whereby an electrostatic area or space M is created between theelectrodes l2, Ar-

ticles or matter of any kind placed in this area are subjected to thecapacity power to an extent that has been found to destroy bacteria andother small animate life. In the present instance, I have shown as anexample a bottle of beer B 5 occupying this area for pasteurizationpurposes. The beer or similar articles may be carried in processionthrough the area as a continuous treatment by a suitable overheadconveyor .l5.

The interposition of a body B in the electro- 10 static field area M, ofcourse, results in an interference that alters the capacity of theelectrodes l2 which would ordinarily affect the power and be compensatedfor by readjustment of the output through condenser 3 to hold the poweruni- 15 form. This variable, however, is also contingent upon both thearea and degree of separation of the electrodes l2 and is very sensitiveto differences in the mass of the interposed article B. It is notpracticable to change either contingent condition to suit individualarticles. I, therefore, provide another means of compensation that isautomatic in operation and does not involve any change in the output ormanipulation of the condenser 3. This means consists, in the presentinstance, of the following:

Hooked up in parallel with the electrodes l2 at a not too remote pointthrough wires I6 is a pair of auxiliary electrodes l1 and I8 which Iprefer to enclose in a vacuum tube l9. One of 30 these, IT, has anoutwardly curved transmitting face turned toward the other, as shown inFig. 1, and is pivotally supported at Hi on a support 20 so that it isfree to, swing toward and from electrode I8. The effect of theelectrostatic action 35 between the two being to draw them together andelectrode I! being free to swing and narrow the gap between it andelectrode l8, when the capacity at I2 is increased through the presenceof article B, electrode l1 compensates by swing- ,ing away fromelectrode l8 which is equivalent to electrodes l2 themselves beingseparated or their areas decreased. The curvature of element l1maintains a tangent line of radiating surface that is constant inrelation to the surface at l8, whatever the degree of separation.Auxiliary electrodes I1 and I8 and support 20 constitute anelectroscopic control unit.

With this arrangement, all electrostatic energy in the field area 'M isrendered constant and is available for dissipation in the matterrepresented by article B, so eliminating the necessity of changes in thefrequency of the radio frequency generator to balance the electrodecapacity changes as the different articles pass 55 under treatment andresulting in a constant cur-. rent flowing through the electrode l2, sothat all articles are treated uniformly regardless of their mass.

I claim as my invention:

1. The combination with a radio frequency generator provided with anoutput inductance element, of a field inductance correlated with thelatter, a pair of capacity electrodes in the circuit of the inductancehaving a uniformly maintained area and degree of separation inoperation, and compensating means in parallel circuit therewith formaintaining uniform power between the field electrodes to overcomeintermediate interference, said compensating means embodying a secondpair of electrodes one of which is pivoted to move toward and from theother in response to the electrostatic stress existing between saidsecond pair 01 electrodes and one of which is provided with a curvedtransmitting surface convexly opposed to the opposite electrode.

2. The combination with a radio frequency I generator provided with anoutput inductance element, of a field inductance correlated with thelatter, a pair of parallel surfaced capacity electrodes in the circuitof the inductance having a uniformly maintained area and degree ofseparation in operation at all times, means for introducing insuccession a plurality of articles to be treated as separate bodies inthe field between the two capacity electrodes, and an automaticcompensating means in parallel circuit therewith for maintaining uniformpower between the field electrodes to overcome intermediate interferenceof different degrees by the respective articles, said compensating meansembodying a second pair of electrodes having a variable in the statedrespects in which the first pair are uniform.

3. In a high-frequency field applicator, a source of high-frequencyvoltage, a pair of capacity plate electrodes connected to said sourceand spaced for the reception therebetween of objects to be treated, andan electroscopic control unit connected in parallel with said plateelectrodes and comprising a pair of. fixed conducting plates mounted inmutual capacity relation and further comprising a movable conductingplate movably supported between said fixed plates by a first one of saidfixed plates in electrical conducting relation with said first one ofsaid fixed plates for variation of the position of said movable platerelative to said fixed plates responsive to the voltage applied to saidfixed plates.

4. In a high-frequency field applicator, a source of high-frequencyvoltage, a pair of capacity plate electrodes connected to said sourceand spaced for the reception therebetween of objects to be treated, andan electroscopic control unit connected in parallel with said plateelectrodes and comprising a pair of. fixed conducting plates mounted inmutual capacity relation and further comprising an arcuate movableconducting plate member movably supported between said fixed plates by afirst one of said fixed plates in electrical conducting relation withsaid first one of said fixed plates for variation of the position ofsaid movable plate member relative to said fixed plates responsive tothe voltage existing across said fixed plates, said arcuate member beingpositioned with its convex side toward the second one of said fixedplates.

5. In a high-frequency field applicator, a source of high-frequencyvoltage, a pair of capacity plate electrodes connected to said sourceand spaced for the reception therebetween of objects to be treated, andan electroscopic control unit connected in parallel with said plateelectrodes and comprising a pair of. fixed conducting plates mounted inmutual capacity relation, a first one of said fixed plates having areentrantly bentover terminal portion, said unit further comprising amovable plate member pivotally conductively supported by said bent-overterminal portion of said first one of said fixed plates between saidplates for variation of the position of said movable plate memberrelative to said fixed plates responsive to the voltage existing acrosssaid fixed plates.

EIMER R. HAYFORD.

